A Possible Mode of Calcium Involvement in Dark- and Light-Induced Leaflet Movements in Cassia fasciculata Michx.

The calcium chelator ethylene glycol-bis-(β-amino ethyl ether)-N,N,N',N'-tetraacetic acid (EGTA) inhibited the dark-induced (scotonastic) and light-induced (photonastic) leaflet movements of Cassia fasciculata, while the calcium-ionophore A 23187 increased the rates of both movements. At concentration as low as 10-6M, the inhibitors of calmodulin-mediated reactions trifluoperazine and calmidazolium (R 24571) also promoted both movements. The present results support the hypothesis that calcium is involved in these movements through a calmodulin-dependent reaction.